The environmental costs to the United States of its dash for shale gas have
been alarming, and potentially catastrophic. A team at Cornell University
reported in 2010 that shale gas production emits more greenhouse gases than
coal, “at least 20 per cent greater” over a 20-year period, largely because
of methane escaping after the fracturing process. In 2009 Wyoming failed to
meet clean air standards for the first time